In this paper, based on the theory of Roberts edge detection operator, as Roberts algorithm is sensitive to noise and it requires artificial specified threshold and other issues, through the image beforehand Otsu processing division after the formation of binary image, and then after Roberts operator sub-processing through matlab simulation experiments, experimental results obtained. Experimental results show that, after Otsu thresholding ideal image after Roberts operator edge extraction, whether the continuity of the image edge information or anti-noise ability has greatly improved.

Edge detection is the first step for image segmentation in image processing. So far there are many algorithms for edge detection. In the paper, a novel algorithm about edge detection is based on the median filtering and Sobel operator. It has strong immunity of noise, edges exquisite and better recognition compared to ordinary sobel operator.